In this paper unsteady methods which are a function of time and steady conditions that are independent of time are used to evaluate the subsurface drainage system established in the upstream lands of the Senejan plain located in the centre of Iran. In order to determine the drain spacing, the steady Hooghoudt model and the unsteady Glover–Dumm, modified Glover and van Schilfgaarde models in rainy periods of 2, 3, 4 and 5 days were used, and the distance between computational drains at two depths install drains (180 and 200 cm) was compared with the results of the subsurface drainage project. To compare the results, the mean absolute error (MAE) and standard error (σ) were used. The results showed that MAE and σ values in the 3‐, 4‐ and 5‐day rainfall in the Glover–Dumm model are 9.75 and 0.196% for the depth of 180 cm and 7.944 and 0.15% for the depth of 200 cm, respectively. The above coefficients obtained in the van Schilfgarde model were 8.098 and 0.162% and 6.685 and 0.134% for 2 days precipitation respectively. The results show that the steady method is not in good agreement with the values of the drain spacing. © 2020 John Wiley & Sons, Ltd.

中文翻译：

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在不渗水层封闭于地面的两种稳态和非稳态流动条件下，评估和确定地下排水空间。案例研究：伊朗Markazi省*

本文采用随时间变化的非稳态方法和与时间无关的稳态条件来评估在伊朗中部塞内延平原上游土地上建立的地下排水系统。为了确定排水沟的间距，使用了稳定的Hooghoudt模型和不稳定的Glover-Dumm模型，改进的Glover和van Schilfgaarde模型在2天，3天，4天和5天的雨季中进行了计算，并且安装了两个深度的计算排水沟之间的距离将排水管（180和200 cm）与地下排水工程的结果进行了比较。为了比较结果，使用了平均绝对误差（MAE）和标准误差（σ）。结果表明，在Glover–Dumm模型的3天，4天和5天降雨中，MAE和σ值分别为180 cm深度和7.944和0时分别为9.75％和0.196％。对于200厘米的深度，分别为15％。在van Schilfgarde模型中获得的上述系数对于2天降水分别为8.098和0.162％以及6.685和0.134％。结果表明，稳定方法与漏极间距的值不一致。分级为4 +©2020 John Wiley＆Sons，Ltd.